Red and Black
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 6865 Accepted Submission(s): 4359
Problem Description
There is a rectangular room, covered with square tiles. Each tile is colored either red or black. A man is standing on a black tile. From a tile, he can move to one of four adjacent tiles. But he can't move on red tiles, he can move only on black tiles.
Write a program to count the number of black tiles which he can reach by repeating the moves described above.
Input
The input consists of multiple data sets. A data set starts with a line containing two positive integers W and H; W and H are the numbers of tiles in the x- and y- directions, respectively. W and H are not more than 20.
There are H more lines in the data set, each of which includes W characters. Each character represents the color of a tile as follows.
'.' - a black tile
'#' - a red tile
'@' - a man on a black tile(appears exactly once in a data set)
Output
For each data set, your program should output a line which contains the number of tiles he can reach from the initial tile (including itself).
Sample Input
6 9
....#.
.....#
......
......
......
......
......
#@...#
.#..#.
11 9
.#.........
.#.#######.
.#.#.....#.
.#.#.###.#.
.#.#..@#.#.
.#.#####.#.
.#.......#.
.#########.
...........
11 6
..#..#..#..
..#..#..#..
..#..#..###
..#..#..#@.
..#..#..#..
..#..#..#..
7 7
..#.#..
..#.#..
###.###
...@...
###.###
..#.#..
..#.#..
0 0
....#.
.....#
......
......
......
......
......
#@...#
.#..#.
11 9
.#.........
.#.#######.
.#.#.....#.
.#.#.###.#.
.#.#..@#.#.
.#.#####.#.
.#.......#.
.#########.
...........
11 6
..#..#..#..
..#..#..#..
..#..#..###
..#..#..#@.
..#..#..#..
..#..#..#..
7 7
..#.#..
..#.#..
###.###
...@...
###.###
..#.#..
..#.#..
0 0
Sample Output
45
59
6
13
59
6
13
思路：确实是简单dfs，初学者一定要多想
#include<stdio.h>
#include<string.h>
char str[][];
int temp[][];
int cnt,h,w;
void dfs(int x,int y)
{
cnt ++;
temp[x][y] =;
if(!temp[x+][y]&& x+ < w)
dfs(x+,y);
if(!temp[x-][y] && x- > -)
dfs(x-,y);
if(!temp[x][y+] && y+ < h)
dfs(x,y+);
if(!temp[x][y-] && y- > -)
dfs(x,y-);
} int main()
{
int i,j,a,b;
while(~scanf("%d%d",&h,&w)&&h+w)
{
cnt =;
for(i =;i < w;i ++)
{
scanf("%s",str[i]);
for(j =;j < h;j ++)
{
if(str[i][j] == '#')
temp[i][j] =;
if(str[i][j] == '.')
temp[i][j] =;
if(str[i][j] == '@')
{
a = i;
b = j;
}
}
}
dfs(a,b);
printf("%d\n",cnt);
}
return;
}